Endoscope

ABSTRACT

There is provided an endoscope that allows treatment, which uses treatment tools, to be performed accurately. 
     An observation window is disposed across a vertical axis in a distal end surface region positioned above a horizontal axis; a first treatment tool outlet port is disposed across the vertical axis in a distal end surface region positioned below the horizontal axis; a second treatment tool outlet port is disposed across the horizontal axis in a distal end surface region positioned below a line, which passes through a center of the observation window and is parallel to the horizontal axis, and in a distal end surface region positioned on a left side of the vertical axis; and a front water supply port is mainly disposed in the distal end surface region positioned below the line, which passes through the center of the observation window and is parallel to the horizontal axis, and in a distal end surface region positioned on a side opposite to the second treatment tool outlet port with respect to a line that passes through a center of the first treatment tool outlet port and is parallel to the vertical axis.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority under 35 U.S.C § 119(a) toJapanese Patent Application No. 2021-055278 filed on Mar. 29, 2021,which is hereby expressly incorporated by reference, in its entirety,into the present application.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an endoscope and more particularly toan endoscope that includes treatment tool outlet ports at a distal endpart of an insertion unit.

2. Description of the Related Art

In an endoscope, various treatment tools are introduced from a treatmenttool inlet port provided on an operation unit and are led out of atreatment tool outlet port opened to a distal end part of the insertionunit, so that various treatments are performed on an object to beexamined. Endoscopic submucosal dissection (ESD) is known as an exampleof the treatment.

JP2002-330920A discloses an endoscope in which different types oftreatment tools are led out of two treatment tool outlet ports opened toa distal end part of an insertion unit to perform treatment.

The endoscope disclosed in JP2002-330920A includes a cutting treatmenttool-protrusion port from which a cutting treatment tool for cuttingbody tissue protrudes and a capturing treatment tool-protrusion portfrom which a capturing treatment tool for capturing cut tissueprotrudes, as the two treatment tool outlet ports. Further, the cuttingtreatment tool-protrusion port and the capturing treatmenttool-protrusion port are opened and disposed at positions with anobservation window interposed therebetween in the diagonal direction ofa visual field mask. Furthermore, a washing water-jetting nozzle forjetting washing water is disposed at a position closer to the cuttingtreatment tool-protrusion port than an intermediate position between thecutting treatment tool-protrusion port and the capturing treatmenttool-protrusion port. The washing water-jetting nozzle jets washingwater in a direction substantially parallel to a direction in which atreatment tool protrudes from the cutting treatment tool-protrusionport.

SUMMARY OF THE INVENTION

In the endoscope disclosed in JP2002-330920A, the capturing treatmenttool protruding from the capturing treatment tool-protrusion port isobserved as an image appearing from the upper side in a screen andfacing the center of the screen in the image of the inside of an objectto be examined that is obtained through the observation window. For thisreason, the capturing treatment tool may serve as an obstacle and maymake it difficult for an operator who performs treatment while lookingat an image to look at a lesion area. Further, in a case where a lesionarea is lifted up by the capturing treatment tool, for example, in acase where the capturing treatment tool is elevated (bent), thecapturing treatment tool may be displayed to be large at the center ofthe screen. Accordingly, even in this case, the capturing treatment toolmay serve as an obstacle and may make it difficult for the lesion areato be seen. As a result, it may be difficult to accurately performtreatment, which uses the cutting treatment tool, by the endoscopedisclosed in JP2002-330920A.

The present invention has been made in consideration of suchcircumstances, and provides an endoscope that allows treatment, whichuses treatment tools, to be performed accurately.

An endoscope according to an aspect of the present invention comprisesan observation window that is provided on a distal end surface of aninsertion unit bendable in an up/down direction and a left/rightdirection and is used to observe an inside of an object to be examined,a first treatment tool outlet port which is provided on the distal endsurface and out of which a first treatment tool is capable of being led,a second treatment tool outlet port which is provided on the distal endsurface and out of which a second treatment tool is capable of beingled, and a front water supply port that is provided on the distal endsurface and jets liquid to a portion to be observed in the object to beexamined. In a case where an axis, which is parallel to the left/rightdirection, of two axes, which pass through a center of the distal endsurface and are orthogonal to each other, is defined as a first axis andan axis thereof parallel to the up/down direction is defined as a secondaxis as the distal end surface is viewed from a front, the observationwindow is disposed across the second axis in a distal end surface regionpositioned above the first axis, the first treatment tool outlet port isdisposed across the second axis in a distal end surface regionpositioned below the first axis, the second treatment tool outlet portis disposed across the first axis in a distal end surface regionpositioned below a line, which passes through a center of theobservation window and is parallel to the first axis, and in a distalend surface region positioned on a left side of the second axis, and thefront water supply port is mainly disposed in the distal end surfaceregion positioned below the line, which passes through the center of theobservation window and is parallel to the first axis, and in a distalend surface region positioned on a side opposite to the second treatmenttool outlet port with respect to a line that passes through a center ofthe first treatment tool outlet port and is parallel to the second axis.

In the aspect of the present invention, it is preferable that, in a casewhere, among four divided regions into which the distal end surface isdivided by the first axis and the second axis, an upper right dividedregion is defined as a first quadrant, an upper left divided region isdefined as a second quadrant, a lower left divided region is defined asa third quadrant, and a lower right divided region is defined as afourth quadrant, the front water supply port is mainly disposed in thefourth quadrant.

In the aspect of the present invention, it is preferable that the secondtreatment tool outlet port has a diameter larger than a diameter of thefirst treatment tool outlet port.

In the aspect of the present invention, it is preferable that theobservation window is mainly disposed in a center-side region which is aregion closer to a center than an outer periphery of the distal endsurface.

In the aspect of the present invention, it is preferable that a distancebetween the center of the observation window and a center of the secondtreatment tool outlet port is longer than a distance between the centerof the observation window and the center of the first treatment tooloutlet port.

In the aspect of the present invention, it is preferable that the distalend surface includes a first surface and a second surface that protrudesin a direction toward a distal end of the insertion unit from the firstsurface, the front water supply port is disposed on the first surface,and the observation window is disposed on the second surface.

In the aspect of the present invention, it is preferable that theendoscope further comprises a first illumination window provided on thesecond surface.

In the aspect of the present invention, it is preferable that, in a casewhere, among four divided regions into which the distal end surface isdivided by the first axis and the second axis, an upper right dividedregion is defined as a first quadrant, an upper left divided region isdefined as a second quadrant, a lower left divided region is defined asa third quadrant, and a lower right divided region is defined as afourth quadrant, an air/water supply nozzle is provided in the secondquadrant.

In the aspect of the present invention, it is preferable that theendoscope further comprises a second illumination window provided on thedistal end surface, and the second illumination window is disposed to beoffset to an outer periphery of the distal end surface on a sideopposite to the center of the distal end surface with respect to a lineconnecting the center of the observation window to a center of theair/water supply nozzle.

In the aspect of the present invention, it is preferable that the secondillumination window is disposed on the second axis.

According to the present invention, treatment using treatment tools canbe performed accurately.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the configuration of an endoscope systemcomprising an endoscope according to an embodiment.

FIG. 2 is a front view of a distal end part of an insertion unit.

FIG. 3 is a diagram illustrating the procedure of a treatment method inESD using the endoscope according to the embodiment.

FIG. 4 is a diagram illustrating the procedure of the treatment methodin ESD using the endoscope according to the embodiment.

FIG. 5 is a diagram illustrating the procedure of the treatment methodin ESD using the endoscope according to the embodiment.

FIG. 6 is a diagram illustrating the procedure of the treatment methodin ESD using the endoscope according to the embodiment.

FIG. 7 is an example of a biological image displayed on a display.

FIG. 8 is a front view of a distal end part of another embodiment.

FIG. 9 is a diagram showing observation images picked up by anobservation optical system.

FIG. 10 is a schematic cross-sectional view of a hand operation unit anda bendable part.

FIG. 11 is a diagram showing a relationship between torque, which isgenerated in a case where the bendable part is bent, and the bendingangle of the bendable part.

FIG. 12 is a diagram showing the connection state of a plurality ofbending pieces that form the bendable part.

FIG. 13 is a cross-sectional view showing the internal structure of abendable part.

FIG. 14 is a cross-sectional view showing the internal structure of abendable part.

FIG. 15 is a cross-sectional view showing the internal structure of abendable part.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An endoscope according to an embodiment of the present invention will bedescribed below with reference to the accompanying drawings.

FIG. 1 is a diagram showing the configuration of an endoscope system 12comprising an endoscope 10 according to an embodiment of the presentinvention. The endoscope system 12 comprises the endoscope 10, aprocessor device 14 for an endoscope, and a display 16.

The endoscope 10 comprises a hand operation unit 18 and an insertionunit 20 that is provided on the distal end side of the hand operationunit 18 and is to be inserted into an object to be examined.

The insertion unit 20 has a major axis Ax extending from a proximal endportion toward a distal end portion, and comprises a soft part 22, abendable part 24, and a distal end part 26 that are arranged in thisorder from a proximal end side toward a distal end side.

A pair of angle knobs 28 and 30, which is used to perform an operationfor bending the bendable part 24, is provided on the hand operation unit18. The pair of angle knobs 28 and 30 is coaxially provided to berotatable. The angle knobs 28 and 30 and the bendable part 24 areconnected to each other by four angle wires (not shown) inserted intothe soft part 22. Accordingly, these angle wires are pushed and pulledby an operation for rotating the angle knobs 28 and 30, so that thebendable part 24 is bent in an up/down direction and a left/rightdirection. Further, the hand operation unit 18 is provided with anair/water supply button 31A and a suction button 31B.

In this specification, a description will be provided using athree-dimensional Cartesian coordinate system having three axisdirections (an X-axis direction, a Y-axis direction, and a Z-axisdirection) orthogonal to each other. That is, in a case where adirection, in which the bendable part 24 faces in a case where thedistal end part 26 is viewed from the hand operation unit 18 and theangle knob 28 for an operation in the up/down direction is movedrotationally in a UP direction, is defined as an upward direction, theupward direction is defined as a Z(+) direction and a downward directionopposite to the upward direction is defined as a Z(−) direction.Further, in a case where a direction, in which the bendable part 24faces in a case where the angle knob 30 for an operation in theleft/right direction is moved rotationally in an R direction, is definedas a right direction, the right direction is defined as an X(+)direction and a left direction is defined as an X(−) direction.Furthermore, a front side at that time (a direction corresponding to thedistal end side in the direction of the major axis Ax) is defined as aY(+) direction, and a rear side (a direction corresponding to theproximal end side in the direction of the major axis Ax) is defined as aY(−) direction. The Y-axis direction including the Y(+) direction andthe Y(−) direction is parallel to the direction of the major axis Ax.

A proximal end portion of a universal cable 32 is connected to the handoperation unit 18, and a distal end portion of the universal cable 32 isprovided with a connector device 34. The connector device 34 isconnected to the processor device 14 for an endoscope.

The processor device 14 for an endoscope comprises a light source device36 and an image processing device 38. The light source device 36 isprovided with a processor-side connector 37 to which the connectordevice 34 is to be connected. Further, the display 16, which displays animage processed by the image processing device 38, is connected to theimage processing device 38. According to this endoscope system 12, lightemitted from the light source device 36 is transmitted through anoptical fiber cable (not shown) and is emitted to the front side (Y(+)direction) from illumination windows 42 and 44 provided on a distal endsurface 40 (see FIG. 2) of the distal end part 26. Further, image light,which is incident from an observation window 46 (see FIG. 2) provided onthe distal end surface 40, is received by, for example, an image pickupelement (not shown) through an observation optical system (not shown)provided on the rear side (Y(−) direction) of the observation window 46.Then, electrical signals, which are photoelectrically converted by theimage pickup element, are processed by the image processing device 38and displayed in the screen of the display 16 as an image in the objectto be examined (hereinafter, referred to as “biological image”). In thedisplay 16, the up/down direction in which the bendable part 24 is to bebent is aligned with a vertical direction in the screen and theleft/right direction in which the bendable part 24 is to be bent isaligned with a horizontal direction in the screen.

Further, the hand operation unit 18 shown in FIG. 1 is provided with afirst treatment tool inlet port 48 into which a first treatment tool canbe introduced and a second treatment tool inlet port 50 into which asecond treatment tool can be introduced. Furthermore, a first treatmenttool channel and a second treatment tool channel (not shown) areinserted into the insertion unit 20. The proximal end portion of thefirst treatment tool channel is connected to the first treatment toolinlet port 48, and the distal end portion thereof is connected to afirst treatment tool outlet port 52 that is opened to the distal endsurface 40 shown in FIG. 2. The proximal end portion of the secondtreatment tool channel is connected to the second treatment tool inletport 50 shown in FIG. 1, and the distal end portion thereof is connectedto a second treatment tool outlet port 54 that is opened to the distalend surface 40 shown in FIG. 2. For example, cutting treatment tools(for example, high-frequency forceps, an ESD knife, and biopsy forceps)for cutting (incising) body tissue are used as the first treatment tool.Further, a treatment tool having multiple functions is used as thesecond treatment tool. As such a treatment tool, there are, for example,grasping forceps having a grasping function and a bending function, anendoscopic suturing device having a suturing function, or the like. Theabove description is the outline of the endoscope 10.

Here, a forward-viewing endoscope in which a distal end part 26 of aninsertion unit 20 is provided with an observation window 46 and twotreatment tool outlet ports (the first treatment tool outlet port 52 andthe second treatment tool outlet port 54 in this embodiment) as in theendoscope 10 according to this embodiment requires the followings toallow treatment, which uses two treatment tools, to be accuratelyperformed.

That is, an operator who operates the endoscope 10 leads two treatmenttools out of the first treatment tool outlet port 52 and the secondtreatment tool outlet port 54 to perform treatment for a lesion areawhile looking at the biological image displayed on the display 16. Forthis reason, it should be avoided that the two treatment tools serve asobstacles and make it difficult for the lesion area to be seen in thebiological image. Accordingly, in a case where components, such as theobservation window 46, the first treatment tool outlet port 52, and thesecond treatment tool outlet port 54, provided on the distal end surface40 of the distal end part 26 shown in FIG. 2 are disposed at suitablearrangement positions shown in FIG. 2, the endoscope 10 according tothis embodiment allows treatment, which uses two treatment tools, to beaccurately performed. An example of the suitable arrangement positionsof the components will be described in detail below.

FIG. 2 is a front view of the distal end part 26. That is, FIG. 2 is adiagram in a case where the distal end surface 40 of the distal end part26 is viewed toward a Y(−) side from a Y(+) side.

As shown in FIG. 2, the illumination windows 42 and 44, the observationwindow 46, the first treatment tool outlet port 52, the second treatmenttool outlet port 54, a front water supply port 56, and an air/watersupply nozzle 58 are provided at predetermined arrangement positions onthe distal end surface 40 of the distal end part 26, respectively. Here,the illumination window 42 corresponds to a first illumination window ofthe present invention, and the illumination window 44 corresponds to asecond illumination window of the present invention. Further, theobservation window 46 corresponds to an observation window of thepresent invention, the first treatment tool outlet port 52 correspondsto a first treatment tool outlet port of the present invention, and thesecond treatment tool outlet port 54 corresponds to a second treatmenttool outlet port of the present invention. Furthermore, the front watersupply port 56 corresponds to a front water supply port of the presentinvention, and the air/water supply nozzle 58 corresponds to anair/water supply nozzle of the present invention.

The observation window 46 is a window that is used to observe the insideof an object to be examined positioned on the front side (Y(+)direction) of the distal end part 26 as already described, and theillumination windows 42 and 44 are disposed with the observation window46 therebetween. Here, for example, in a case where the diameter of thedistal end part 26 is in the range of 12.5 to 13.0 mm, each of theobservation window 46 and the illumination windows 42 and 44 is formedwith a diameter of, for example, about 1.5 to 2.0 mm.

The first treatment tool outlet port 52 is an opening portion out ofwhich the already described cutting treatment tool (first treatmenttool) can be led to the front side. The second treatment tool outletport 54 is an opening portion out of which, for example, the alreadydescribed grasping forceps (second treatment tool) can be led to thefront side. The second treatment tool outlet port 54 is formed with adiameter of, for example, about 3.5 to 4.0 mm to make the graspingforceps, which have a diameter larger than the diameter of the cuttingtreatment tool, pass therethrough. That is, the diameter of the secondtreatment tool outlet port 54 is larger than the diameter (for example,about 3.0 to 3.5 mm) of the first treatment tool outlet port 52 throughwhich only the cutting treatment tool may pass. The first treatment tooloutlet port 52 also functions as a suction port that sucks liquid andthe like in the object to be examined by the operation of the suctionbutton 31B shown in FIG. 1.

The front water supply port 56 is an opening portion that jets liquid toa portion to be observed (for example, a lesion area) in the object tobe examined, and is formed with a diameter of, for example, about 1.0 to1.5 mm. The front water supply port 56 is connected to a water supplyconnector 35, which is provided on the connector device 34 (see FIG. 1),through a water supply tube (not shown). A water supply device (notshown) is connected to the water supply connector 35, and liquid issupplied to the front water supply port 56 through the water supply tubein a case where the water supply device is driven.

The air/water supply nozzle 58 is a nozzle that jets liquid and airmainly to the observation window 46. Liquid or air is selectivelysupplied to the air/water supply nozzle 58 in response to the operationof the air/water supply button 31A shown in FIG. 1.

Here, in a case where the distal end surface 40 is viewed from the frontas shown in FIG. 2, an axis, which is parallel to the left/rightdirection, of two axes, which pass through a center C of the distal endsurface 40 and are orthogonal to each other, is defined as a horizontalaxis H and an axis thereof parallel to the up/down direction is definedas a vertical axis V. In this case, the observation window 46 isdisposed across the vertical axis V in a distal end surface region 40Apositioned above the horizontal axis H. The first treatment tool outletport 52 is disposed across the vertical axis V in a distal end surfaceregion 40B positioned below the horizontal axis H, and the secondtreatment tool outlet port 54 is disposed across the horizontal axis Hin a distal end surface region 40C positioned below a line H1, whichpasses through a center 46A of the observation window 46 and is parallelto the horizontal axis H, and in a distal end surface region 40Dpositioned on the left side of the vertical axis V. Further, the frontwater supply port 56 is disposed in the distal end surface region 40Cpositioned below the line H1, which passes through the center 46A of theobservation window 46 and is parallel to the horizontal axis H, and in adistal end surface region 40E positioned on a side opposite to thesecond treatment tool outlet port 54 with respect to a line V1 thatpasses through a center 52A of the first treatment tool outlet port 52and is parallel to the vertical axis V. Here, the horizontal axis Hcorresponds to a first axis of the present invention and the verticalaxis V corresponds to a second axis of the present invention.

Next, an example of a treatment method using the endoscope 10 accordingto the embodiment will be described with reference to FIGS. 3 to 6. Theprocedure of the treatment method in ESD is shown in FIGS. 3 to 6.Further, high-frequency forceps 100 including a pair of claws 102, whichcan be opened and closed, at distal end portions thereof as shown inFIG. 6 are used as the first treatment tool. The pair of claws 102 isopened and closed by an operation unit (not shown) for thehigh-frequency forceps 100. In a case where high-frequency current ismade to flow between the pair of claws 102 in a state where the pair ofclaws 102 is closed and biological tissue is grasped by the pair ofclaws 102, the biological tissue is cauterized and incised.

Further, grasping forceps 200, which include a bendable part 202 and apair of grasping parts 204 at the distal end portion thereof as shown inFIG. 3, are used as the second treatment tool. The bendable part 202 isbent by an operation unit (not shown) for the grasping forceps 200, andthe pair of grasping parts 204 is opened and closed by the operationunit.

First, the operator orally inserts the insertion unit 20 of theendoscope 10 shown in FIG. 1 into the object to be examined. Then, in acase where the distal end part 26 is positioned on the lateral side of alesion area 300 of a mucosal layer as shown in FIG. 3, the operatorinserts the high-frequency forceps 100 (see FIG. 6) into the firsttreatment tool channel from the first treatment tool inlet port 48 ofthe endoscope 10 (see FIG. 1). After that, the operator inserts thegrasping forceps 200 (see FIG. 3) into the second treatment tool channelfrom the second treatment tool inlet port 50, and leads the pair ofgrasping parts 204 and the bendable part 202 of the grasping forceps 200forward out of the second treatment tool outlet port 54 as shown in FIG.3. Then, the operator operates the operation unit (not shown) for thegrasping forceps 200 to grasp the lesion area 300 by the pair ofgrasping parts 204 as shown in FIGS. 3 and 4.

Next, as shown in FIG. 5, the operator operates the operation unit (notshown) for the grasping forceps 200 to bend the bendable part 202 upward(Z(+) direction). Accordingly, the pair of grasping parts 204 iselevated, so that the lesion area 300 grasped by the pair of graspingparts 204 is lifted up.

Next, in a state where the lesion area 300 is lifted up as shown in FIG.5, the operator leads the high-frequency forceps 100, which are insertedinto the first treatment tool channel, to the front side out of thefirst treatment tool outlet port 52 as shown in FIG. 6. Then, theoperator advances the pair of claws 102 of the high-frequency forceps100 to the lower portion of the lesion area 300 to incise the lowerportion of the lesion area 300 by the pair of claws 102. After that,after the lesion area 300 is completely incised, the operator pulls thegrasping forceps 200 to the Y(−) side to take the lesion area 300 out ofthe endoscope 10 in a state where the lesion area 300 is grasped by thepair of grasping parts 204. The above description is an example of thetreatment method in ESD.

FIG. 7 shows an example of a biological image 400 displayed on thedisplay 16 in the treatment. In the description of the biological image400 shown in FIG. 7, a so-called clock position, which is representedfrom 1 o'clock to 12 o'clock, will be used in addition to the up/down (Zaxis) and the left/right (X axis).

According to the biological image 400 shown in FIG. 7, thehigh-frequency forceps 100 led out of the first treatment tool outletport 52 (see FIG. 2) are observed as an image facing the lesion area300, which is positioned at the center of the screen, from the positionof about 6 o'clock on the lower side in the screen. Further, thegrasping forceps 200 led out of the second treatment tool outlet port 54(see FIG. 2) are observed as an image facing the lesion area 300, whichis positioned at the center of the screen, from the position of about 4o'clock on the lower right side in the screen. Accordingly, since thehigh-frequency forceps 100 and the grasping forceps 200 are displayed inthe biological image 400 without overlapping with each other, thehigh-frequency forceps 100 and the grasping forceps 200 are easily seen.As a result, treatment, which uses the high-frequency forceps 100 andthe grasping forceps 200, can be performed accurately.

That is, in the endoscope 10 according to the embodiment, as shown inFIG. 2, the observation window 46 is disposed across the vertical axis Vin the distal end surface region 40A positioned above the horizontalaxis H, the first treatment tool outlet port 52 is disposed across thevertical axis V in the distal end surface region 40B positioned belowthe horizontal axis H, and the second treatment tool outlet port 54 isdisposed across the horizontal axis H in the distal end surface region40C positioned below the line H1, which passes through the center 46A ofthe observation window 46 and is parallel to the horizontal axis H, andin the distal end surface region 40D positioned on the left side of thevertical axis V. That is, the observation window 46 and the firsttreatment tool outlet port 52 are disposed at middle positions of thedistal end surface 40 in the left/right direction (positions along thevertical axis V), the first treatment tool outlet port 52 is disposedbelow the observation window 46, and the second treatment tool outletport 54 is disposed at a position offset to an outer periphery 40F ofthe distal end surface 40 from between the observation window 46 and thefirst treatment tool outlet port 52 (a position on the diagonally lowerside (a position on the diagonally lower left side in FIG. 2) of theobservation window 46). Accordingly, in a case where an operatorperforms treatment while looking at the lesion area 300 in thebiological image 400 shown in FIG. 7, the operator can accuratelyperform treatment, which uses the high-frequency forceps 100 and thegrasping forceps 200, while looking at the lesion area 300 withoutinterference between the high-frequency forceps 100 and the graspingforceps 200.

Further, in the endoscope 10 according to the embodiment, as shown inFIG. 2, the first treatment tool outlet port 52 is disposed across thevertical axis V in the distal end surface region 40B positioned belowthe horizontal axis H and the second treatment tool outlet port 54 isdisposed across the horizontal axis H in the distal end surface region40D positioned on the left side of the vertical axis V. That is, thesecond treatment tool outlet port 54 is disposed above the firsttreatment tool outlet port 52 and at a position on the left side of thefirst treatment tool outlet port 52 (a position on the diagonally upperleft side of the first treatment tool outlet port 52 in FIG. 2).Accordingly, the bendable part 202 and the pair of grasping parts 204are observed as an image that is moved to the right end side from thecenter in the biological image 400 shown in FIG. 7 in a case where thebendable part 202 of the grasping forceps 200 is bent to lift up thelesion area 300 as shown in FIGS. 5 and 6. As a result, since the imageregion of the grasping forceps 200 in the biological image 400 isreduced in size, the high-frequency forceps 100 are more easily seen.Therefore, incising treatment using the high-frequency forceps 100 canbe performed accurately.

Further, in the endoscope 10 according to the embodiment, as shown inFIG. 2, the observation window 46 is disposed across the vertical axis Vand the second treatment tool outlet port 54 is disposed in the distalend surface region 40D positioned on the left side of the vertical axisV. That is, the second treatment tool outlet port 54 is disposed at aposition on the left side of the observation window 46. Accordingly, ina case where a part of light emitted from the illumination windows 42and 44 is reflected by the pair of grasping parts 204, becomes scatteredlight, and is received by the image pickup element from the observationwindow 46, halation (a phenomenon in which an image becomes white) mayoccur. However, since the pair of grasping parts 204 is positioned onthe right end side of the biological image 400 shown in FIG. 7, theamount of scattered light received by the image pickup element isreduced. As a result, halation can be suppressed.

Furthermore, in the endoscope 10 according to the embodiment, the frontwater supply port 56 is disposed in the distal end surface region 40Cpositioned below the line H1, which passes through the center 46A of theobservation window 46 and is parallel to the horizontal axis H, and inthe distal end surface region 40E positioned on a side opposite to thesecond treatment tool outlet port 54 with respect to the line V1 thatpasses through a center 52A of the first treatment tool outlet port 52and is parallel to the vertical axis V. That is, the front water supplyport 56 is disposed below the observation window 46 and is disposed at aposition offset to the outer periphery 40F of the distal end surface 40from between the observation window 46 and the first treatment tooloutlet port 52 (a position on the diagonally lower side (a position onthe diagonally lower right side in FIG. 2) of the observation window46). According to the biological image 400 shown in FIG. 7, liquid 60jetted from the front water supply port 56 (see FIG. 2) is observed asan image of liquid jetted to the lesion area 300, which is positioned atthe center of the screen, from a position on the lower side in thescreen (the position of 7 to 8 o'clock). Accordingly, the liquid 60 andthe high-frequency forceps 100 are displayed in the biological image 400without overlapping with each other. As a result, in a case where anoperator performs treatment while observing the lesion area 300 in thebiological image 400, the operator can observe the liquid 60 jetted tothe lesion area 300 while performing treatment on the lesion area 300with the high-frequency forceps 100.

Here, a comparative example, which is contrasted with the endoscope 10according to the embodiment, will be briefly described. For example, ina case where a first treatment tool outlet port is disposed in thedistal end surface region positioned below the observation window and asecond treatment tool outlet port is disposed in the distal end surfaceregion positioned above the observation window in the direction of thevertical axis V shown in FIG. 2, grasping forceps led out of the secondtreatment tool outlet port are observed as an image facing the center ofa screen from the position of, for example, 11 to 1 o'clock on the upperside in the screen in a biological image displayed on the display. Forthis reason, the grasping forceps may serve as an obstacle and may makeit difficult for an operator who performs treatment while looking at thebiological image 400 to look at a lesion area. Further, in a case wherea lesion area is lifted up by the grasping forceps, the grasping forcepsmay be displayed to be large in the image. Accordingly, even in thiscase, the grasping forceps may serve as an obstacle and may make itdifficult for the lesion area to be seen. As a result, it may bedifficult to accurately perform incising treatment, which useshigh-frequency forceps, in the comparative example.

In contrast, in the endoscope 10 according to the embodiment, theobservation window 46 is disposed across the vertical axis V in thedistal end surface region 40A positioned above the horizontal axis H,the first treatment tool outlet port 52 is disposed across the verticalaxis V in the distal end surface region 40B positioned below thehorizontal axis H, and the second treatment tool outlet port 54 isdisposed across the horizontal axis H in the distal end surface region40C positioned below the line H1, which passes through the center 46A ofthe observation window 46 and is parallel to the horizontal axis H, andin the distal end surface region 40D positioned on the left side of thevertical axis V. That is, the observation window 46 and the firsttreatment tool outlet port 52 are disposed at middle positions of thedistal end surface 40 in the left/right direction, the first treatmenttool outlet port 52 is disposed below the observation window 46, and thesecond treatment tool outlet port 54 is disposed at a position offset tothe outer periphery 40F of the distal end surface 40 from between theobservation window 46 and the first treatment tool outlet port 52.According to such configuration, since the high-frequency forceps 100led out of the first treatment tool outlet port 52 are observed as animage facing the lesion area 300, which is positioned at the center ofthe screen, from the position of 6 o'clock on the lower side in thescreen and the grasping forceps 200 led out of the second treatment tooloutlet port 54 are observed as an image facing the center of the screenfrom the position of about 4 o'clock on the lower right side in thescreen, the high-frequency forceps 100 and the grasping forceps 200 arenot observed as an image that faces the center of the screen from aposition on the upper side in the screen as in the comparative example.Accordingly, since the high-frequency forceps 100 and the graspingforceps 200 do not interfere with each other and the grasping forceps200 do not make it difficult for the lesion area 300 to be seen, anoperator can accurately perform treatment, which uses the high-frequencyforceps 100 and the grasping forceps 200, while looking at the lesionarea 300.

Configuration in which the front water supply port 56 is completelyincluded in a region in which the distal end surface region 40C and thedistal end surface region 40E overlap with each other has been shown inFIG. 2, but the configuration of the endoscope is not necessarilylimited thereto. The front water supply port 56 may be mainly disposedin the distal end surface region 40C and the distal end surface region40E.

Here, the above-mentioned “mainly disposed” means a case where themajority (half or more) of the front water supply port 56 is included inthe region in which the distal end surface region 40C and the distal endsurface region 40E overlap with each other. That is, the configurationof the endoscope is not limited to the configuration in which the frontwater supply port 56 is completely included in the overlapping region,and configuration in which at least a part of the front water supplyport 56 is disposed outside the overlapping region also corresponds tothe case of the above-mentioned “mainly disposed” as long as themajority of the front water supply port 56 is included in theoverlapping region. A case where a description is made using “mainlydisposed” in the following description also has the same meanings asdescribed above.

The specific arrangement form of the observation window 46, the firsttreatment tool outlet port 52, the second treatment tool outlet port 54,the front water supply port 56, the illumination windows 42 and 44, andthe air/water supply nozzle 58 disposed on the distal end surface 40shown in FIG. 2 will be described below with reference to FIG. 2.

First, the specific arrangement position of the front water supply port56 will be described. In a case where the distal end surface 40 of theendoscope 10 is divided into four regions by the horizontal axis H andthe vertical axis V, an upper right divided region is defined as a firstquadrant 70A, an upper left divided region is defined as a secondquadrant 70B, a lower left divided region is defined as a third quadrant70C, and a lower right divided region is defined as a fourth quadrant70D among the divided regions, the front water supply port 56 is mainlydisposed in the fourth quadrant 70D.

Accordingly, since the liquid 60 jetted from the front water supply port56 (see FIG. 2) is observed as an image facing the lesion area 300,which is positioned at the center of the screen, from the position of 7to 8 o'clock on the lower left side in the screen in the biologicalimage 400 shown in FIG. 7, the high-frequency forceps 100 are easilyseen.

The observation window 46 is disposed in a center-side region 70F thatis a region closer to the center C than the outer periphery 40F of thedistal end surface 40. According to this arrangement, for example, thehigh-frequency forceps 100 can be observed as an image facing the lesionarea 300, which is positioned at the center of the screen, from theposition of about 6 o'clock on the lower side in the screen and thegrasping forceps 200 can be observed as an image facing the lesion area300, which is positioned at the center of the screen, from the positionof about 4 o'clock on the lower right side in the screen. That is, sincethe high-frequency forceps 100 as a main treatment tool can be observedfrom the lower side in the screen and the grasping forceps 200 as asub-treatment tool can be observed from the lower right side in thescreen, treatment using the high-frequency forceps 100 and the graspingforceps 200 can be performed accurately. Further, since the observationwindow 46 is excessively away from the second treatment tool outlet port54 in a case where, on the contrary, the observation window 46 isdisposed in an outer region (not shown) that is a region closer to theouter periphery 40F than the center C of the distal end surface 40,treatment using the grasping forceps 200 led out of the second treatmenttool outlet port 54 may be affected. Accordingly, in a case where theobservation window 46 is disposed in the center-side region 70F,treatment using the high-frequency forceps 100 and the grasping forceps200 can be performed accurately.

Meanwhile, since the grasping forceps 200 have multiple functions(bending function) as compared to the high-frequency forceps 100, thediameter of the grasping forceps 200 is larger than the diameter of thehigh-frequency forceps 100. For this reason, the second treatment tooloutlet port 54 has a diameter larger than the diameter of the firsttreatment tool outlet port 52. Furthermore, since the second treatmenttool outlet port 54 is disposed in the third quadrant 70C, an imageregion of the biological image 400, which is occupied by the image ofthe grasping forceps 200, can be reduced in size. Accordingly, since thehigh-frequency forceps 100 are more easily seen, treatment using thehigh-frequency forceps 100 can be performed accurately.

Further, the air/water supply nozzle 58 is disposed in the secondquadrant 70B. Accordingly, the second quadrant 70B, which is empty interms of a space, can be effectively used as an arrangement space forthe air/water supply nozzle 58. As a result, the diameter of the distalend part 26 can be reduced.

Furthermore, the distal end surface 40 comprises a first surface 41A anda second surface 41B that protrudes in a direction (Y(+) direction)toward the distal end of the insertion unit 20 from the first surface41A, the front water supply port 56 is disposed on the first surface41A, and the observation window 46 is disposed on the second surface41B. Here, the first surface 41A corresponds to a first surface of thepresent invention, and the second surface 41B corresponds to a secondsurface of the present invention. In this example, the second surface41B having a fan shape in plan view is formed in a part of the firstquadrant 70A and a part of the second quadrant 70B, and the firstsurface 41A is formed in the other part of the first quadrant 70A, theother part of the second quadrant 70B, the third quadrant 70C, and thefourth quadrant 70D.

Since the observation window 46 is disposed on the second surface 41Band the front water supply port 56 is disposed on the first surface 41A,halation, which is caused by the remaining water of the liquid 60 raisedfrom the front water supply port 56 in the Y(+) direction, and the likecan be suppressed. Specifically, when the liquid 60 has been completelysupplied from the front water supply port 56, the remaining water of theliquid 60 is raised in the Y(+) direction at the opening of the frontwater supply port 56 due to the influence of the surface tensionthereof. As a result, there is a concern that the raised remaining watermay glare in the screen or halation may be caused by the reflection ofapplied light by the raised remaining water. In contrast, since theendoscope 10 according to the embodiment has configuration in which theobservation window 46 is disposed on the second surface 41B and thefront water supply port 56 is disposed on the first surface 41A, theglare of the remaining water caused by the raised remaining water andhalation can be suppressed. As a result, a good image can be displayed.

Further, the illumination window 42 (first illumination window) isfurther disposed on the second surface 41B in the configuration in whichthe observation window 46 is disposed on the second surface 41B and thefront water supply port 56 is disposed on the first surface 41A.Accordingly, it is possible to suppress that the remaining water of thefront water supply port 56 adheres to the illumination window 42. As aresult, a reduction in the amount of illumination light, which is causedby the adhesion of the remaining water to the illumination window 42,and halation can be suppressed.

The illumination window 44 corresponding to the second illuminationwindow is disposed on the first surface 41A. The illumination window 44is positioned on a side opposite to the side where the front watersupply port 56 is disposed with the observation window 46 therebetween,and is disposed at a position farther from the front water supply port56 than the illumination window 42. For this reason, since the remainingwater of the front water supply port 56 is more difficult to adhere tothe illumination window 44 than the illumination window 42, theillumination window 44 can be disposed on the first surface 41A. It goeswithout saying that the illumination window 44 may be disposed on thesecond surface 41B like the illumination window 42.

Further, the illumination window 44 (second illumination window) isdisposed to be offset to the outer periphery 40F of the distal endsurface 40 on a side opposite to the center C of the distal end surface40 with respect to a line L1 connecting the center 46A of theobservation window 46 to a center 58A of the air/water supply nozzle 58.That is, the illumination window 44 is disposed at a position away fromthe second treatment tool outlet port 54 with respect to the observationwindow 46. The reason why this arrangement is desirable will bedescribed below.

The bendable part 202 of the grasping forceps 200 led out of the secondtreatment tool outlet port 54 is bent upward as shown in FIG. 5. At thistime, in a case where the illumination window 44 is disposed close tothe second treatment tool outlet port 54, a part of light emitted fromthe illumination window 44 may be reflected by the pair of graspingparts 204, become scattered light, and be received by the image pickupelement from the observation window 46, so that halation may occur.Since the endoscope 10 according to the embodiment has configuration inwhich the illumination window 44 is disposed to be offset to a positionaway from the second treatment tool outlet port 54 as described above,it is possible to suppress that the scattered light is received by theimage pickup element. As a result, since it is possible to suppresshalation that is caused by the grasping forceps 200 led out of thesecond treatment tool outlet port 54, a good image can be displayed.

An aspect in which the illumination window 44 is disposed to completelydeviate from the line L1 to the outer periphery 40F has been describedin the embodiment as a preferred aspect, but the present invention isnot limited thereto. At least a center 44A of the illumination window 44may deviate from the line L1 to the outer periphery 40F. That is, thesame effects as those of the embodiment can be obtained even in anaspect in which the illumination window 44 is disposed at a positionoverlapping with the line L1.

Further, it is preferable that the illumination window 44 is disposed onthe vertical axis V in the above-mentioned offset disposition. In thiscase, it is possible to suppress that illumination light emitted fromthe illumination window 44 is blocked by the pair of grasping parts 204even though the bendable part 202 of the grasping forceps 200 is bent.As a result, a bright and good image can be displayed. An aspect inwhich the center 44A of the illumination window 44 is disposed at aposition overlapping with the vertical axis V has been described in theembodiment as a preferred aspect, but the present invention is notlimited thereto. At least a part of the illumination window 44 may bedisposed on the vertical axis V. That is, the same effects as those ofthe embodiment can be obtained even in an aspect in which theillumination window 44 is disposed at a position overlapping with thevertical axis V.

Another Embodiment of Distal End Part

FIG. 8 is a front view of a distal end part of another embodiment.

According to FIG. 8, the arrangement positions of the observation window46, the first treatment tool outlet port 52, and the second treatmenttool outlet port 54 are different from the arrangement positions of theobservation window 46, the first treatment tool outlet port 52, and thesecond treatment tool outlet port 54 shown in FIG. 2 but basicarrangement positions are the same as the arrangement positions shown inFIG. 2. That is, as shown in FIG. 8, the observation window 46 isdisposed across the vertical axis V in the distal end surface region 40Apositioned above the horizontal axis H, the first treatment tool outletport 52 is disposed across the vertical axis V in the distal end surfaceregion 40B positioned below the horizontal axis H, and the secondtreatment tool outlet port 54 is disposed across the horizontal axis Hin the distal end surface region 40C positioned below a line H1, whichpasses through the center 46A of the observation window 46 and isparallel to the horizontal axis H, and in the distal end surface region40D positioned on the left side of the vertical axis V. Further, thefront water supply port 56 is disposed in the distal end surface region40C positioned below the line H1, which passes through the center 46A ofthe observation window 46 and is parallel to the horizontal axis H, andin the distal end surface region 40E positioned on a side opposite tothe second treatment tool outlet port 54 with respect to the line V1that passes through the center 52A of the first treatment tool outletport 52 and is parallel to the vertical axis V. The same effects asthose of the configuration shown in FIG. 2 are obtained from thisconfiguration, and the endoscope further has the followingconfiguration.

As shown in FIG. 8, the observation window 46 and the first treatmenttool outlet port 52 are shifted to an X(−) side from the center C of thedistal end surface 40 and are shifted toward the horizontal axis H inthe Z-axis direction from the configuration shown in FIG. 2, so that adistance between the observation window 46 and the first treatment tooloutlet port 52 is reduced. According to such configuration, theobservation window 46, the first treatment tool outlet port 52, and thesecond treatment tool outlet port 54 are disposed so that a distance D2between the center 46A of the observation window 46 and a center 54A ofthe second treatment tool outlet port 54 is longer than a distance D1between the center 46A of the observation window 46 and the center 52Aof the first treatment tool outlet port 52.

Accordingly, since the bendable part 202 and the pair of grasping parts204 are moved to the right end side of the biological image 400 in acase where the bendable part 202 of the grasping forceps 200 is bent andthe pair of grasping parts 204 is elevated, it is difficult for thebendable part 202 and the pair of grasping parts 204 to be seen from thebiological image 400. As a result, treatment using the high-frequencyforceps 100 can be performed accurately.

Several preferred aspects related to the endoscope 10 according to theembodiment will be described below.

As for Adjustment of Mounting Position of Observation Window

First, a case where the first treatment tool outlet port 52 is disposedimmediately below the observation window 46 in the direction of thevertical axis V will be described. The lead-out position of thetreatment tool to be observed in an observation image is changed in theobservation image depending on the mounting position of an observationoptical system that is disposed on the rear side (Y(−) direction) of theobservation window 46. An example thereof will be described withreference to FIG. 9.

Reference numeral IXA of FIG. 9 denotes an observation image 502 that isobtained in a case where a line (not shown) connecting the center 46A ofthe observation window 46 (that is, the center of the observationoptical system) to the center 52A (see FIG. 2) of the first treatmenttool outlet port 52 is inclined to the right from a line parallel to thevertical axis V by an angle of 1° or less as the distal end surface 40is viewed in the Y(+) direction. Reference numeral IXB denotes anobservation image 504 that is obtained in a case where a line connectingthe center 46A of the observation window 46 to the center 52A of thefirst treatment tool outlet port 52 is inclined to the right from a lineparallel to the vertical axis V by an angle of 10° as the distal endsurface 40 is viewed in the Y(+) direction. Reference numeral IXCdenotes an observation image 506 that is obtained in a case where a lineconnecting the center 46A of the observation window 46 to the center 52Aof the first treatment tool outlet port 52 is inclined to the left froma line parallel to the vertical axis V by an angle of 7° as the distalend surface 40 is viewed in the Y(+) direction. For convenience ofdescription, the aspect of a case where the center 46A of theobservation window 46 and the center of the observation optical systemare aligned with each other on the same straight line in advance will bedescribed in this example, but the position of the center of theobservation optical system shall be adjusted in a case where the center46A of the observation window 46 and the center of the observationoptical system are not aligned with each other.

The high-frequency forceps 100 are observed in the observation image 502so as to be led from the lower portion (the position of 6 o'clock) ofthe observation image 502 to the center of the observation image 502. Incontrast, the high-frequency forceps 100 are observed in the observationimage 504 so as to be led from the lower left of the observation image504, and are observed in the observation image 506 so as to be led fromthe lower right of the observation image 506.

As described above, the high-frequency forceps 100 are seemed to be ledfrom different positions in the observation image depending on themounting position of the observation window 46. For this reason, thereis a possibility that an operator's technique is affected.

Accordingly, in order to solve such a problem, the mounting position ofthe observation window 46 is adjusted and the inclination of a lineconnecting the center 46A of the observation window 46 to the center 52Aof the first treatment tool outlet port 52 is set within 3° from thevertical axis V so that the lead-out position of the high-frequencyforceps 100 in the observation image is seen constant. Therefore, anoperator can perform treatment with a stable technique.

As a method of adjusting the mounting position of the observation window46, an operator can adjust the position of the observation window usingan adjustment jig while looking at an image picked up by the observationoptical system.

As for Bending Operation Mechanism

Next, an example of a bending operation mechanism for bending thebendable part 24 among the components of the hand operation unit 18 willbe described. FIG. 10 is a schematic cross-sectional view of the handoperation unit 18, and a part of the bendable part 24 is also shown as across-sectional view in FIG. 10. Further, a bending operation mechanism,which bends the bendable part 24 in the up/down direction, of bendingoperation mechanisms for bending the bendable part 24 is shown in FIG.10, and a bending operation mechanism for bending the bendable part 24in the left/right direction will not be shown since being the samemechanism. The former bending operation mechanism will be describedbelow and the description of the latter bending operation mechanism willbe omitted.

As shown in FIG. 10, for example, the bendable part 24 includes aplurality of substantially cylindrical bending pieces 552 and aplurality of rivet pins 554 connecting adjacent bending pieces 552, andadjacent bending pieces 552 are connected to each other to moverotationally about the rivet pins 554 as an axis.

Meanwhile, for example, as shown in FIGS. 13 to 15, a pair of anglewires 556 used to bend the bendable part 24 upward and downward and apair of angle wires 556 used to bend the bendable part 24 leftward andrightward are inserted into the soft part 22 and the bendable part 24 inaddition to built-in components, such as a first treatment tool channel714, a second treatment tool channel 716, a liquid feed tube 708, aliquid supply tube 710, a gas supply tube 712, a signal cable 702, andlight guides 704 and 706. The two pairs of angle wires 556 are disposedalong the direction of the major axis Ax of the insertion unit 20, andare engaged with the bending pieces 552 by being inserted into holes 720of pins 722 a, 722 b, 722 c, and 722 d provided inside each of the rivetpins 554 of the bendable part 24.

Further, each of the distal end portions of the pair of angle wires 556for operation in the up/down direction of the two pairs of angle wires556 is fixed to the distal end part 26, and the proximal end portions ofthe pair of angle wires 556 are joined to a pair of sleeves 557 foroperation in the up/down direction shown in FIG. 10, respectively.Accordingly, in a case where the pair of angle wires 556 are operated tobe pushed and pulled through the pair of sleeves 557, the bendable part24 is bent in the up/down direction.

The bending operation mechanism 558 for operation in the up/downdirection, which is provided in the hand operation unit 18, includes asprocket 560 and a chain 562 wound around the sprocket 560. The pair ofsleeves 557 is joined to both end portions of the chain 562.

The sprocket 560 is connected to the angle knob 28 for operation in theup/down direction (see FIG. 1) through a rotating shaft 560A, and isrotated with an operation for rotating the angle knob 28. Accordingly,the pair of angle wires 556 is operated to be pushed and pulled throughthe chain 562 and the pair of sleeves 557. That is, one of the pair ofangle wires 556 is pulled to the proximal end side, and the otherthereof is sent to the distal end side.

Here, stoppers 564A and 564B, which restrict the movement of the sleeves557 and 557 to the proximal end side by coming into contact with thesleeves 557 and 557, are provided on the proximal end side of thesleeves 557 and 557. The positions of the stoppers 564A and 564B areadapted to be adjustable respectively, and the movement of the sleeves557 and 557 is restricted by the stoppers 564A and 564B. As a result,the maximum bending angle of the bendable part 24 in the up/downdirection is determined.

Further, with regard to the stoppers 564A and 564B, the position of thestopper 564A, which restricts the movement of the sleeve on the upperside (Z(+) side), is set on the proximal end side of the position of thestopper 564B, which restricts the movement of the sleeve on the lowerside (Z(−) side). Accordingly, the bendable part 24 is bent at an upwardangle larger than a downward angle. As a result, in a case where thebendable part 24 is bent upward, a body wall on a side opposite to theinsertion direction of the insertion unit 20 can be observed. In thiscase, the downward bending angle is reduced (for example, a bendingangle on the upper side is 210° but a bending angle on the lower side is90°). However, since the upper side is mainly used in the endoscope,there is no problem with the use of the endoscope.

Meanwhile, even though the angle knob 28 is operated in an endoscope(for example, an endoscope simultaneously using two treatment tools)that requires a large pulling force (large torque) in a case where thebendable part 24 is to be bent, the angle wire 556 may not contribute toan operation for bending the bendable part 24 since the angle wire 556has been elongated. In order to prevent this problem, the position ofthe stopper 564A, which restricts the movement of the sleeve on theupper side, is disposed closer to the proximal end. As a result, sincethe angle wire 556 including the amount of elongation of the angle wire556 can be pulled, the bendable part can be bent upward even in theendoscope requiring large torque. In a case where the positions of thestoppers 564A and 564B are adjusted depending on the magnitude of torquein this way, it is possible to use common components without usingdedicated components depending on the magnitude of the torque.

As for Bendable Part

Next, an example of the configuration of the bendable part 24 will bedescribed. FIG. 11 is a diagram (graph) showing a relationship betweentorque (pulling force), which is generated in a case where the bendablepart 24 is to be bent, and the bending angle of the bendable part 24.FIG. 12 is a diagram showing the connection state of the plurality ofbending pieces of the bendable part.

In an endoscope having a torque fluctuation shown by a line LA of FIG.11 (here, referred to as an endoscope A), the bendable part 24 can bebent with torque that gradually increases up to a certain angle.However, the endoscope has a point of inflection at which larger torqueis required in a case where a bending angle exceeds a certain bendingangle (190° in the case of the line LA). Accordingly, in this endoscopeA, an operation for bending the bendable part 24 is performed withoutany problem in a case where a bending angle increases up to 190°.However, since larger torque is required in a case where a bending angleexceeds 190°, a load is applied on an operator. Further, since the anglewire 556 may be elongated even though the operator pulls the angle wirewith large torque, a predetermined bending angle may not be capable ofbeing obtained from the pulling force.

The line LA is measured in a state where the built-in components areincluded in the bendable part, but the tendency of the line LA is thesame even in a state where the built-in components are not included.Accordingly, in a case where torque and a bending angle are measuredwith the bendable part alone, which does not include built-incomponents, in the endoscope A, it has been confirmed that the bendablepart has a point of inflection at an angle of 225°.

Here, the bendable part 24 has configuration to be described below andan angle at a point of inflection in a state where built-in componentsare not included in the bendable part 24 is set to be larger than 225°to solve the above-mentioned problem. The configuration of the bendablepart 24 will be described below.

That is, as shown in FIG. 12, a pair of connecting pieces 602 formed inthe shape of a tongue is provided on each bending piece 552 of thebendable part 24 in a circumferential direction and protrudes from eachbending piece 552 in the Y-axis direction. The pair of connecting pieces602 is disposed at intervals of 180° in the circumferential direction ofthe bending piece 552. The connecting pieces 602 of adjacent bendingpieces 552 overlap with each other and rivet pins 606 are mounted onthrough-holes 604 formed in the connecting pieces 602, so that theadjacent bending pieces 552 are connected to each other. Accordingly,the plurality of bending pieces 552 are connected to each other to moverotationally in the up/down direction through two rivet pins 606 and 606that are provided in the left/right direction.

For example, the following can be performed in order to set the bendingangle of the bendable part 24 to an angle larger than that in therelated art. That is, an inclination angle of an end portion 608 withrespect to the Z axis is set to be large so that end portions 608 and608 of the adjacent bending pieces 552 facing each other in the Y-axisdirection are away from each other in the Y-axis direction. Accordingly,in a case where the bendable part 24 is bent, the bending angle of thebendable part 24 is larger than that in the related art. As a result,the point of inflection of the bendable part 24 alone can be set to, forexample, 225° or more, and the point of inflection of the bendable part24 including the built-in components can be set to, for example, 205° ormore (see an endoscope B shown by a line LB of FIG. 11).

It is preferable that intermediate bending pieces 552, which exclude adistal end-side bending piece 552 connected to the distal end part 26and a proximal end-side bending piece 552 connected to the soft part 22,are applied as a bending piece having a large inclination angle of theend portion 608 among the plurality of bending pieces 552 connected toeach other in the Y-axis direction.

That is, the position of the distal end-side bending piece 552 in theY-axis direction is a position at which a tube as the sheath of thebendable part 24 is fixed to the distal end part 26, and is a portion atwhich stiffness is high since an adhesive is hardened. Accordingly,since large torque is required in order to bend this portion (a portionat which stiffness is high) in a case where the inclination angle of theend portion 608 is set to be large in the distal end-side bending piece552, it is preferable that a bending piece in the related art is appliedas the distal end-side bending piece 552.

Further, the position of the proximal end-side bending piece 552 in theY-axis direction is a position that serves as the starting point ofbending of the bendable part 24. Accordingly, in a case where theinclination angle of the end portion 608 is set to be large in theproximal end-side bending piece 552, the distal end part 26 of theendoscope 10 is raised high at the position of the bending piece 552.For this reason, a curvature obtained in a case where the bendable part24 is bent is reduced, so that it is difficult to invert the bendablepart 24 with a large curvature. That is, since the observation range ofthe endoscope 10 is narrowed, it is preferable that a bending piece inthe related art is applied as the proximal end-side bending piece 552.

As for Internal Structure of Bendable Part

Next, the preferred internal structure of the bendable part 24 will bedescribed. The illumination windows 42 and 44, the observation window46, the first treatment tool outlet port 52, the second treatment tooloutlet port 54, the air/water supply nozzle 58, and the front watersupply port 56 are disposed on the distal end surface 40 of theendoscope 10 as described above. These are connected to the handoperation unit 18 through various cables and various channels(hereinafter, referred to as built-in components) that are inserted intothe bendable part 24 and the soft part 22.

The illumination windows 42 and 44, the observation window 46, the firsttreatment tool outlet port 52, the second treatment tool outlet port 54,the air/water supply nozzle 58, and the front water supply port 56 arefixed to the distal end part 26. However, since the bendable part 24 isto be bent, it is preferable that the built-in components provided inthe bendable part 24 are disposed without being fixed.

Incidentally, in a case where an operation for bending the bendable part24 is repeated, the built-in components may be moved in the bendablepart 24. In this case, there may be problems that the built-incomponents kink (are entangled or twisted), the cables are disconnected,the arrangement of the built-in components in the bendable part isdisturbed with respect to the arrangement of the components on thedistal end surface, and the like.

Accordingly, it is preferable that the endoscope has the followingconfiguration to prevent the arrangement of the built-in componentsprovided in the bendable part 24 from being disturbed.

(1) The outer diameters of the first treatment tool channel 714 and thesecond treatment tool channel 716 are increased.

FIG. 13 is a cross-sectional view showing the internal structure of thebendable part, and is a view of the bendable part viewed in the Y(+)direction from the Y(−) direction. In a case where the inside of thebendable part 24 is divided in half in the Z-axis direction according tothe arrangement of the respective components on the distal end surface40, the signal cable 702, the light guides 704 and 706, the liquid feedtube 708 for feeding water to the front water supply port 56, the liquidsupply tube 710 for supplying liquid to the air/water supply nozzle 58,and the gas supply tube 712 for supplying gas to the air/water supplynozzle 58 are disposed in a region, which corresponds to the Z(+)direction, of the divided two regions. Further, the first treatment toolchannel 714 and the second treatment tool channel 716 are disposed in aregion corresponding to the Z(−) direction. Furthermore, pins 722 a, 722b, 722 c, and 722 d, which include holes 720 into which the angle wires556 used to bend the bendable part 24 are to be inserted, are providedon the upper, lower, left, and right sides on the inner periphery of thebendable part 24.

In the bendable part 24 shown in FIG. 13, the outer diameter of each ofthe first treatment tool channel 714 and the second treatment toolchannel 716 is set to be large and a distance between the pins 722 b and722 d facing each other in the X-axis direction is set to be shorterthan the sum of the outer diameter of the first treatment tool channel714 and the outer diameter of the second treatment tool channel 716.

In addition, it is preferable that the first treatment tool channel 714has an outer diameter allowing the first treatment tool channel 714 notto move to a region corresponding to the Z(+) direction by allowing thefirst treatment tool channel 714 to be in contact with the pin 722 dprovided on the X(−) side and the second treatment tool channel 716, andthe second treatment tool channel 716 has an outer diameter allowing thesecond treatment tool channel 716 not to move to a region correspondingto the Z(+) direction by allowing the second treatment tool channel 716to be in contact with the pin 722 b provided on the X(+) side and thefirst treatment tool channel 714.

According to the above-mentioned configuration, it is possible toprevent both the first treatment tool channel 714 and the secondtreatment tool channel 716 from moving to the region corresponding tothe Z(+) direction. Further, it is possible to prevent the signal cable702, the light guides 704 and 706, the liquid feed tube 708, the liquidsupply tube 710, and the gas supply tube 712 from moving to the regioncorresponding to the Z(−) direction by the first treatment tool channel714 and the second treatment tool channel 716. As a result, it ispossible to prevent the arrangement of the built-in components providedin the bendable part 24 from being disturbed.

(2) The pins extend toward the central portion.

FIG. 14 is a diagram illustrating another embodiment that prevents thedisturbance of the arrangement. In the embodiment shown in FIG. 14, pins722 b and 722 d provided to face each other in the X-axis directionextend toward the center of the bendable part 24. Further, a distancebetween the pins 722 b and 722 d facing each other is set to be shorterthan the outer diameter of the first treatment tool channel 714 and theouter diameter of the second treatment tool channel 716.

Accordingly, it is possible to prevent the first treatment tool channel714 and the second treatment tool channel 716 from moving to a regioncorresponding to the Z(+) direction from the pins 722 d and 722 bprovided in the X-axis direction. As a result, it is possible to preventthe arrangement of the built-in components provided in the bendable part24 from being disturbed.

Further, since a force applied to the pins 722 b and 722 d can bedispersed in a case where the shapes of the pins 722 b and 722 d of eachbending piece 552 of the bendable part 24 are set to the above-mentionedshapes, it is possible to prevent the pins 722 b and 722 d from beingdamaged.

(3) A partition member is provided in the bendable part.

FIG. 15 is a diagram illustrating still another embodiment that preventsthe disturbance of the arrangement. In the embodiment shown in FIG. 15,a partition member 724 is provided in a region corresponding to the Z(+)direction. The partition member 724 is a component that is housed in theregion corresponding to the Z(+) direction, and is provided to surroundthe signal cable 702, the light guides 704 and 706, the liquid feed tube708, the liquid supply tube 710, and the gas supply tube 712.

Accordingly, it is possible to prevent various cables and variouschannels from being exchanged between the region corresponding to theZ(+) direction and the region corresponding to the Z(−) direction. As aresult, it is possible to prevent the arrangement of the built-incomponents from being disturbed.

A position where the partition member 724 is provided can be provided atany position in the bendable part 24. The partition member 724 can beinstalled by a method including fixing the partition member 724 by spotwelding, assembling the bendable part, and inserting the partitionmember into the bendable part for assembly.

The endoscope according to the embodiment has been described above, butthe present invention may include some improvements or modificationswithout departing from the scope of the present invention.

EXPLANATION OF REFERENCES

-   -   10: endoscope    -   12: endoscope system    -   14: processor device for endoscope    -   16: display    -   18: hand operation unit    -   20: insertion unit    -   22: soft part    -   24: bendable part    -   26: distal end part    -   28: angle knob    -   30: angle knob    -   31A: air/water supply button    -   31B: suction button    -   32: universal cable    -   34: connector device    -   35: water supply connector    -   36: light source device    -   37: processor-side connector    -   38: image processing device    -   40: distal end surface    -   40A: distal end surface region    -   40B: distal end surface region    -   40C: distal end surface region    -   40D: distal end surface region    -   40E: distal end surface region    -   40F: outer periphery    -   41A: first surface    -   41B: second surface    -   42: illumination window    -   44: illumination window    -   44A: center    -   46: observation window    -   46A: center    -   48: first treatment tool inlet port    -   50: second treatment tool inlet port    -   52: first treatment tool outlet port    -   52A: center    -   54: second treatment tool outlet port    -   54A: center    -   56: front water supply port    -   58: air/water supply nozzle    -   58A: center    -   60: liquid    -   70A: first quadrant    -   70B: second quadrant    -   70C: third quadrant    -   70D: fourth quadrant    -   70F: center-side region    -   100: high-frequency forceps    -   102: claw    -   200: grasping forceps    -   202: bendable part    -   204: grasping part    -   300: lesion area    -   400: biological image    -   502: observation image    -   504: observation image    -   506: observation image    -   552: bending piece    -   554: rivet pin    -   556: angle wire    -   557: sleeve    -   558: bending operation mechanism    -   560: sprocket    -   560A: rotating shaft    -   562: chain    -   564A: stopper    -   564B: stopper    -   602: connecting piece    -   604: through-hole    -   606: rivet pin    -   608: end portion    -   702: signal cable    -   704: light guide    -   706: light guide    -   708: liquid feed tube    -   710: liquid supply tube    -   712: gas supply tube    -   714: first treatment tool channel    -   716: second treatment tool channel    -   720: hole    -   722 a: pin    -   722 b: pin    -   722 c: pin    -   722 d: pin    -   724: partition member    -   Ax: major axis    -   C: center    -   H: horizontal axis    -   H1: line parallel to horizontal axis    -   V: vertical axis    -   V1: line parallel to vertical axis    -   L1: line    -   LA: line    -   LB: line    -   D1: distance    -   D2: distance

What is claimed is:
 1. An endoscope comprising: an observation windowthat is provided on a distal end surface of an insertion unit bendablein an up/down direction and a left/right direction and is used toobserve an inside of an object to be examined; a first treatment tooloutlet port which is provided on the distal end surface and out of whicha first treatment tool is capable of being led; a second treatment tooloutlet port which is provided on the distal end surface and out of whicha second treatment tool is capable of being led; and a front watersupply port that is provided on the distal end surface and jets liquidto a portion to be observed in the object to be examined, wherein in acase where an axis, which is parallel to the left/right direction, oftwo axes, which pass through a center of the distal end surface and areorthogonal to each other, is defined as a first axis and an axis thereofparallel to the up/down direction is defined as a second axis as thedistal end surface is viewed from a front, the observation window isdisposed across the second axis in a distal end surface regionpositioned above the first axis, the first treatment tool outlet port isdisposed across the second axis in a distal end surface regionpositioned below the first axis, the second treatment tool outlet portis disposed across the first axis in a distal end surface regionpositioned below a line, which passes through a center of theobservation window and is parallel to the first axis, and in a distalend surface region positioned on a left side of the second axis, and thefront water supply port is mainly disposed in the distal end surfaceregion positioned below the line, which passes through the center of theobservation window and is parallel to the first axis, and in a distalend surface region positioned on a side opposite to the second treatmenttool outlet port with respect to a line that passes through a center ofthe first treatment tool outlet port and is parallel to the second axis.2. The endoscope according to claim 1, wherein in a case where, amongfour divided regions into which the distal end surface is divided by thefirst axis and the second axis, an upper right divided region is definedas a first quadrant, an upper left divided region is defined as a secondquadrant, a lower left divided region is defined as a third quadrant,and a lower right divided region is defined as a fourth quadrant, thefront water supply port is mainly disposed in the fourth quadrant. 3.The endoscope according to claim 1, wherein the second treatment tooloutlet port has a diameter larger than a diameter of the first treatmenttool outlet port.
 4. The endoscope according to claim 1, wherein theobservation window is mainly disposed in a center-side region that is aregion closer to a center than an outer periphery of the distal endsurface.
 5. The endoscope according to claim 1, wherein a distancebetween the center of the observation window and a center of the secondtreatment tool outlet port is longer than a distance between the centerof the observation window and the center of the first treatment tooloutlet port.
 6. The endoscope according to claim 1, wherein the distalend surface includes a first surface and a second surface that protrudesin a direction toward a distal end of the insertion unit from the firstsurface, the front water supply port is disposed on the first surface,and the observation window is disposed on the second surface.
 7. Theendoscope according to claim 6, further comprising: a first illuminationwindow that is provided on the second surface.
 8. The endoscopeaccording to claim 1, wherein in a case where, among four dividedregions into which the distal end surface is divided by the first axisand the second axis, an upper right divided region is defined as a firstquadrant, an upper left divided region is defined as a second quadrant,a lower left divided region is defined as a third quadrant, and a lowerright divided region is defined as a fourth quadrant, an air/watersupply nozzle is provided in the second quadrant.
 9. The endoscopeaccording to claim 8, further comprising: a second illumination windowthat is provided on the distal end surface, wherein the secondillumination window is disposed to be offset to an outer periphery ofthe distal end surface on a side opposite to the center of the distalend surface with respect to a line connecting the center of theobservation window to a center of the air/water supply nozzle.
 10. Theendoscope according to claim 9, wherein the second illumination windowis disposed on the second axis.